## 21 June 2018

### Square root of five

$\sqrt 5$ is an irrational number which is present in the golden ratio.

It is also the measure of the hypotenuse of a right triangle whose other two sides measuring $1$ and  $2$ units.

We have also:

$\sqrt 5 = e^{i\pi}+2\phi$;

$\sqrt 5 \approx \frac{85}{38}$.